Macrocycles mononuclear

Mononuclear complexes of palladium and platinum in the +3 oxidation state have only recently been unequivocally characterized [157]. The major advance has come in complexes with macrocyclic ligands such as 1,4,7-trithiacyclononane (ttcn) and 1,4,7-triazacyclononane (tacn) (Figure 3.96). 

From this perspective they reported the structure (complex (791) Cu-Cu 10.061 A) of a m-xylyl-based TACN ligand.583 Structures of four mononuclear copper(I) complexes ((792)-(795)), supported by tridentate macrocycle, were also reported by this group. They investigated their oxygenation behavior and in each case clean formation of side-on peroxo-dicopper(II) species was demonstrated.416... 

The ability of thioether macrocyclic complexes (and especially those of [9]aneS3) to support multi-redox behaviour at the coordinated metal centre is particularly notable. This allows a series of reversible stepwise one-electron oxidation and/or reduction processes, and stabilization of highly unusual transition metal oxidation states e.g. mononuclear [Pd([9]aneS3)2]2+/3+/4+,149 [Au([9]aneS3)2]+/2+/3+,150 [Ni([9]aneS3)2]2+/3+,151 and [Rh([9]aneS3)2]+/2+/3+.152 It appears to be the ability of the crown thioethers to readily adjust their... 

Fig. 32. Mononuclear Ni(II) and Zn(II) complexes of acyclic and macrocyclic polyamine-thiophenolate ligands (224).

Another example of a mononuclear complex is the dicationic Cr(III) complex [CrinH2L19(OAc)]2+ (47). This complex is obtained when (L19)2 is treated with CrCl2 and NaOAc in methanol followed by oxidation in air (226). The Cr ion in 47 is coordinated to three N and two S atoms of (L19)2 and an O atom of a monodentate acetate coligand in an octahedral manner as shown in Fig. 33. To our knowledge, mononuclear complexes of macrocyclic thiophenolate Schifif-bases have not yet been documented in the literature (227). 

A number of pendant arm ligand derivatives based on hexamine macrocyclic backbones have been reported." One such species was formed by the [2 -f 2] Schiff base condensation between 3,3-iminobis(propylamine) and diformyl-p-cresol followed by sodium borohydride reduction of the four imine functions so generated. Potentiometric studies indicate that a range of both mononuclear and dinuclear species are formed in solution with manganese(II) incorporating various both protonated and nonprotonated forms of the ligand. 

Other high-spin, mononuclear manganese(II) complexes of mixed oxygen nitrogen macrocycles have been reported. ... 

Linkage isomerizations, osmium, 37 335-339 Linked cubane clusters, Fe—S proteins, biological implications, 38 55-56 Linked macrocyclic ring systems, 45 75 dinuclear systems, 45 89-95 triaza ring systems, 45 76-87 Li—N—Li linkages, 37 100-101 Lipoxygenase, inhibitors, 36 41 Liquid-liquid extraction of metal ions, 9 1-80 with acidic P-based extractants, 9 34-48 with acidic P-based extractants dinuclear, 9 47-48 mononuclear, 9 34-47 with amines and amine oxides, 9 49-56 complexes in, 9 68-71 countercurrent extraction method, 9 15-25... 

Mononuclear Complexes with Porphyrins, SchifTBases, Phthalocyanine, and Related Macrocyclic Ligands... 

The spectra and redox potentials of the binuclear bismacrocyclic Ni(II) complexes, 17-19 and 20, are similar to those of the corresponding mononuclear complexes of 9 and 3a, respectively. That is, the ligand field strength of the complexes is only slightly affected by the type or the length of bridging chain that links the two macrocyclic units. 

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